Monatin is a naturally occurring sweet amino acid isolated and extracted from roots of shrubs in South Africa, and has a structure shown below. Monatin has sweetness potency which is dozens to thousands of times stronger than that of sucrose, and is anticipated to be used as a sweetener. In addition to (2S, 4S) isomer of monatin, there are three other optical isomers, i.e., (2S, 4R)-isomer, (2R, 4S)-isomer and (2R, 4R)-isomer. All of the isomers have been confirmed to have sweetness potency which is hundreds of times to thousands of times stronger than that of sucrose.

Methods for producing monatin have been reported in the following documents:
(1) U.S. Pat. No. 5,994,559
(2) South Africa Patent No. ZA-874288
(3) Japan Patent No. 2002-60382
(4) Tetrahedron Letters, 42(39):6793-6796, 2001
(5) Organic Letters, 2(19):2967-2970, 2000
(6) Synthetic Communication, 24(22):3197-3211, 1994
(7) Synthetic Communication, 23(18):2511-2526, 1993